1. Field of the Invention
This invention relates to a silicon controlled rectifier (SCR) lamp supply trigger circuit, responsive to control circuitry, to produce trigger currents for the SCR which transmits the required voltage to illumination lamps in a document image capturing system.
2. Description of the Prior Art
Prior circuits for supplying current pulses to trigger a silicon controlled rectifier (SCR) transmitting voltage to illumination lamps have principally relied on an additional power supply. This dependence resulted in the need to generate large current pulses to trigger the SCR while the control circuitry regulating the lamp supply voltage required only low levels of current. When the same large current supply was used for both applications, signal interference in the control and trigger circuits appeared. However, the dual power supply approach was recognized to be a costly solution to the large trigger current pulse requirements of the SCR. In addition, more room was needed to contain the separate transformer and associated parts for the current pulse generation.
The invention to be disclosed offers a single voltage supply trigger circuit which will provide the large trigger currents for the SCR without electrically interfering with the power requirements of the control and trigger circuits regulating the lamp supply voltage to the illumination lamps.